Purpose:
To describe Optical Frequency Domain Imaging (OFDI), an ultra-fast OCT system at a longer wavelength providing better tissue penetration, and its imaging characteristics in patients with neovascular age-related macular degeneration (AMD).
Methods:
An ultra-fast ophthalmic imaging system at a longer wavelength (1050 nm) than commonly used for retinal imaging has been developed, providing superior penetration into the retinal and choroidal layers. OFDI uses a wavelength-tunable light source and a single photodetector. The spectrally resolved interference is detected as a function of time by rapidly tuning the wavelength of the source. A-scans were acquired at a rate of 30,000 per second. Patients with neovascular AMD were evaluated with color fundus photography, fluorescein angiography, and OFDI imaging. Institutional review board approval was obtained.
Results:
At 1050 nm, OFDI provided images extending deep into the choroid, near the scleral interface. The faster acquisition speed allowed imaging of large tissue volumes while preserving sensitivity. OFDI provided detailed structural information over large retinal areas corresponding to features observed in color fundus photos and fluorescein angiography. OFDI demonstrated features associated with exudative AMD, including pigment, subretinal fluid, choroidal neovascularization, suspect choroidal neovascularization, cystic changes, changes in the scattering properties of the photoreceptors, and retinal pigment epithelial detachments.Figure: OFDI cross sectional image. A: drusen, B: blood clot, C: subretinal fluid, D: confirmed CNV from FA, E: RPE detachment, F: suspected CNV.
Conclusions:
OFDI is an ultra-fast imaging technology, which provides higher speed and deeper penetration of the retinal and choroidal structures than conventional OCT. OFDI can provide accurate diagnostic information and may aid in the evaluation and treatment of neovascular AMD.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • age-related macular degeneration • imaging/image analysis: clinical